Recently, information processing system bases are spreading widely, which utilize virtualization techniques such as server virtualization and storage virtualization to integrate multiple business systems in the resources of a physical computer, to thereby enhance the efficiency of use of resources of the whole data center. The systems which had been operated in a fixed manner in resources are isolated from the physical resources via virtualization, and migrated over physical resources according to the status of operation of the business applications, so that workloads can be dynamically balanced.
Especially, according to a computer system called an IaaS (Infrastructure as a Service) cloud, where a self-service portal is adopted, a user is capable of provisioning a desirable application to the respective virtual servers, or is capable of changing the configuration of the virtual server according to their demands, without concerning the administrator.
On the other hand, as a result of enhancing the consolidation ratio through virtualization technique, the business systems that are logically used by different users often have unintentional impact on performances. Multiple applications can be configured to share a single physical resource due to the virtualization technique, but on the other hand, the capacity, bandwidth or processing performance of the physical resource is restricted physically, so that excessive load may cause a bottleneck of the performance.
In order to eliminate such instability of performance, for example, a countermeasure is taken to allocate physical resources with higher priority to sections causing bottleneck. For example, according to Patent Literature 1, a technique is disclosed to search other virtual servers having similar states of use of resources with respect to a virtual server having added resources thereto, and to perform adjustment so that the resource will not become the bottleneck by applying an operation to add the same type of resource.
From the viewpoint of the provider side of the cloud service, confronting requests exist, to consolidate as much business systems as possible to a smaller number of physical resources in order to improve the efficiency of use thereof, and at the same time, to allocate enough resources exclusively to stabilize the performance.
Therefore, in an environment utilizing the virtualization technique, the problem to be solved is the coexistence of use efficiency versus performance stability. For example, Patent Literature 2 discloses an art of allocating only necessary amount of resources to business applications by determining the amount of resources to be added based on a performance prediction, to thereby improve the overall system's use efficiency.